Airflow Regulator

ABSTRACT

A louvre-type airflow regulator ( 10 ) for a mine passage comprises a plurality of louvre blades ( 12, 14, 16 ). Each blade is adapted for mounting in a frame ( 20 ). Each blade can pivot in the frame around a lengthwise axis between a predetermined position in which the louvre blades combine to close or restrict at least a portion of the passage, and an open position in which air is able to readily flow between the louvre blades and through the passage. A biasing mechanism is provided for acting on each louvre blade such that, in use, each louvre blade can be maintained in the predetermined position until a predetermined airflow against the louvre blades is reached.

TECHNICAL FIELD

A louvre-type airflow regulator is disclosed. The regulator findsparticular application in mining shafts, tunnels, raises, roadways etc(hereafter “mine passages”) to control or regulate airflow therethrough.

BACKGROUND ART

Underground mines may have a number of raises that act as a conduit forfresh air, with raises formed on an air intake side of an ore body andon an air return or opposite side of the ore body. Airflow at variouslevels in a mine is then controlled by airflow regulators arranged,inter alia, at the entrances or exits of these raises.

Known airflow regulators used in mines are referred to as drop-boardregulators and have been in use for some time. An airflow regulator isalso known that includes vertical louvres pivotally mounted in a steelframe.

Drop-board regulators may comprise a steel H section frame fabricatedinto compartments of a convenient size. Into each compartment hardwoodboards are dropped down between the flanges of the H section. In thisway the aperture of the regulator can be adjusted in area, therebyaltering the quantity of airflow that is allowed into a given section ofa mine.

Drop-board regulators require manual adjustment. In addition, before anevent such as stope firing or blasting takes place, and where it isbelieved that the blast may physically damage the regulator, a miner hasto physically remove all the boards, being a heavy, arduous and timeconsuming task. Major stope firings can result in large volumes of airbeing forced through mine passages, with the pressures generated beingsufficient to permanently damage mine ventilation structures.

SUMMARY OF DISCLOSURE

In one aspect there is provided a louvre-type airflow regulator for amine passage comprising:

-   -   a plurality of louvre blades, each adapted for mounting in a        frame and pivoting therein around a lengthwise axis between a        predetermined position in which the louvre blades combine to        close or restrict at least a portion of the passage, and an open        position in which air is able to readily flow between the louvre        blades and through the passage portion; and    -   a biasing mechanism for acting on each louvre blade such that,        in use, each louvre blade can be maintained in the predetermined        position until a predetermined airflow against the louvre blades        is reached.

The biasing mechanism can provide the regulator with air “overpressure”protection resulting from eg. a major stope firing or blasting event,without the need for regulator demounting. Thus, at least some of theshortcomings of drop-board regulators can be addressed. The use oflouvre blades also allows for remote regulator control.

The terminology “predetermined airflow” can include within its scopepredetermined air pressure, and typically though not exclusively relatesto an increase in airflow/pressure from a firing or blasting (eg. astope firing or blasting).

The predetermined position typically corresponds to a closed position ora partially opened position of the blades (the blades in the partiallyopened position being more closed than in the open position). Thepartially opened position may be assumed, for example, when the louvreis in a normal airflow control mode of operation.

The open position typically corresponds to a blade fully open position,although the blades may be less than fully open, but yet be more openthan the predetermined position, hence the terminology “open position”includes such a configuration.

The biasing mechanism may comprise:

(i) a weighting arrangement operable on each louvre blade and that tendsto cause it to pivot into the predetermined position;(ii) a spring mechanism that positively urges each louvre blade to pivotinto the predetermined position; and/or(iii) a strut mechanism that positively urges each louvre blade to pivotinto the predetermined position.

In (i) the weighting arrangement can comprise one or more weightsoperatively coupled to each louvre blade via a respective linkage,whereby due to gravity the weight(s) draw down on the linkages andthereby urge each louvre blade into the predetermined position, but atthe predetermined airflow the louvre blades then act on each linkage andurge the weight(s) up as each louvre blade moves towards the openposition.

For example, the weighting arrangement can comprise one or two weights,with each weight having the linkages extending therefrom at intervalsspaced along the weight, and with each linkage being coupled to arespective louvre blade at a coupling that is pivotally mounted to theframe at the same point as the blade pivotal mounting.

In (ii) the spring mechanism can comprise one, a number, or a respectivespring for each blade. The spring(s) pull each louvre blade into thepredetermined position, but at the predetermined airflow the louvreblades act on and stretch against the spring(s) as each louvre blademoves towards the open position. For example, the spring(s) can extendbetween the frame and a location on or connected to a louvre blade at oradjacent to a leading or trailing edge of the blade. Also, when thelouvres are interconnected via linkages, only one or a few springs maybe required to pull the louvre blades into the predetermined position(eg. with the spring then acting on the linkages).

The spring(s) may, for example, comprise a helical, leaf or other springtype.

In (iii) the strut mechanism can comprise a gas strut that is connectedto a linkage mechanism that acts on the louvre blades to urge them intothe predetermined position. At the predetermined airflow the louvreblades can act on the linkage mechanism which in turn acts against thegas strut as each louvre blade moves towards the open position. Theconnection between the gas strut and the linkage mechanism can beadjustable such that the louvre blades can either be fully or partiallyclosed by the operation of the gas strut.

The regulator may further comprise a control mechanism to separately andindependently control the position of each louvre blade during normalairflow conditions in the mine passage (ie. to control airflow otherthan that generated by a blast). Typically the biasing mechanism isadapted to not interfere with normal airflow control and typically thecontrol mechanism is adapted to not interfere with opening of the louvreblades at the predetermined airflow or with biasing mechanism bladereturn to the predetermined position.

The control mechanism may comprise a remotely controlled adjustmentmechanism or a manual adjustment mechanism. The control mechanism canemploy actuators that are eg. electrically operated and that may beremotely controlled (eg. via a fibre optic communication system at asurface of the mine). The manual adjustment mechanism can provide formulti-blade positioning, with the louvre blades being maintained at agiven partially opened position using eg. a locking pin.

The regulator can further comprise the frame. The frame can, forexample, form part of a module, with a plurality of such modules beingmountable in a larger frame arranged in the passage. The regulatormodules can also be configured such that they can be located intoexisting drop-board frame structures after removing the timber dropboards.

Alternatively a complete set of modules can be made up within a suitable(eg. purpose-built) frame that can be attached to the mine opening byvarious means. These means can, for example, comprise a plurality ofmounting pins/bolts that extend from eg. the larger frame and that areadapted for fastening with respect to adjacent wall(s) of the minepassage. The pins/bolts can then be used for the mounting of suitableformwork that provides a backing for the application (eg. via spraying)of a cementitious binder (eg. shotcrete), the pins/bolts, formwork andbinder then providing a structural wall to support the frame in thepassage.

Each module in the set may have a plurality of selectively extendablesecuring pins arranged around its periphery such that, when the moduleis mounted in the larger passage frame, extension of the securing pinssecures the module to the passage frame, and retraction of the securingpins enables module detachment from the passage frame. Each module mayalso have lifting points formed therein that enable it to be lifted intoand out of the passage frame

In one arrangement of the regulator the louvre blades move when subjectto a large air blast, and thereafter move back to the predeterminedposition. For the intake louvres, where normal ventilation air helpskeep the louvre blades shut, the blade return mechanism (eg. thecounterweight size) can be reduced or of less scale.

The regulator may further comprise a stop for preventing blade pivotalmovement beyond the open position (typically a blade fully openposition). The stop may comprise a dampener or shock absorber, to dampenor absorb the momentum of a pivoting blade.

Whilst the mechanism can be employed with in-use vertically (orotherwise) extending louvre blades, usually the blades extend generallyhorizontally in the frame in use.

BRIEF DESCRIPTION OF DRAWINGS

Notwithstanding any other forms that may fall within the scope of thelouvre-type airflow regulator as defined in the Summary, specificembodiments of the regulator will now be described, by way of exampleonly, with reference to the accompanying drawings in which:

FIG. 1 shows a front view of a louvre-type regulator;

FIG. 2 shows a front view of a louvre-type regulator module for use,inter alia, in the regulator of FIG. 1;

FIGS. 3A and 3B respectively show side schematic views of a louvre-typeregulator in closed (shut) and open configurations, and illustrating theoperation of a weighting mechanism for the regulator;

FIG. 4 shows a schematic plan view the weighting mechanism of FIG. 3;

FIGS. 5 and 6 respectively show front and plan views of a drop-boardregulator frame but suitable for receiving one or more louvre-typeregulator modules therein;

FIGS. 7A and 7B respectively show side schematic views of intake andexhaust louvre-type regulators in a mine passage and illustrating theaction of blast and ventilation airflows;

FIG. 8 shows a side schematic view of two louvre blades of an exhaustlouvre-type regulator in a closed configuration, and illustrating theblast and ventilation forces thereon;

FIG. 9 shows a front perspective view of a louvre-type regulator module;

FIG. 10 shows a rear perspective view of the module of FIG. 9;

FIG. 11 shows a perspective detail of the module of FIG. 9;

FIG. 12 shows a front detail of the module of FIG. 9;

FIG. 13 shows a rear view of another louvre-type regulator module;

FIG. 14 shows a side detail of the biasing mechanism for the module ofFIG. 13;

FIG. 15 shows a front detail of the biasing mechanism for the module ofFIG. 13;

FIG. 16 shows a side detail of the biasing mechanism of FIG. 15;

FIG. 17 shows a front detail of a securing mechanism for the module ofFIG. 13; and

FIG. 18 shows a front detail of both the securing mechanism and alifting feature for the module of FIG. 13.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Drop-board regulators are used to control air-flow to an undergroundmine and are typically located in (or at the entrance/exit of) so-calledmine raises. These raises are typically located on each side of an orebody and comprise a number of air intake (or inlet) raises and a numberof air return (or exhaust) raises. Where a stope firing or blastingoccurs proximate to known drop-board regulators these can be damaged andrendered ineffective if the boards are not removed.

Louvre-based regulators have now been developed to overcome theshortcomings of drop-board regulators, including the heavy weight of thedrop boards, and the arduous and time-consuming task of moving boards.Such louvre-based regulators allow for control of airflow in minepassages, but also provide for air overpressure to be accommodated (eg.as a result of proximate stope firing or blasting) and, thereafter, forlouvre blade return. Thus, regulator demounting prior to a stope firingor blasting need not occur. In addition, louvre regulators can becontrolled remotely (eg. from a control room at the mine surface) toregulate normal airflow levels in mine passages.

Louvre-based modules for retrofitting to in-situ drop-board regulatorframes were proposed (Example 2) as a means of reducing installationcost and time.

A first stand-alone louvre design (Example 3) was proposed thatincorporated manually controllable adjustment mechanisms of the louvreblades. It was noted that, due to the nature of manual controlmechanisms, in some mine applications this design could be compromisedby a large and/or proximate stope firing, resulting in sever airoverpressure, leading to permanent louvre damage. For example, if eachlouvre blade is locked in a set position (eg. partial or fully openedposition) it may still sustain damage due to the turbulent andnon-laminar nature of airflow that can move therepast as a result ofstope firing and blasting (ie. forcing the louvre blade against itslock).

A second stand-alone louvre design (Example 4) was proposed thatincorporated self-adjusting louvre blades without manual control, withthe second design being generally applicable in mines and beingresistant to large and/or proximate stope firing. In this regard, theself-adjusting louvre blades were able to pivot in response to turbulentand non-laminar airflow moving therepast, but could still beindependently controlled during normal airflow situations (ie.maintained at a number of set positions).

Referring now to FIGS. 1 to 4, a louvre regulator 10 is schematicallydepicted for mounting at or in a mine passage (eg. an air intake orexhaust raise). The regulator 10 comprises a plurality of differentsized louvre blades 12, 14 and 16. Whilst the regulator can employvertically extending louvre blades, the blades 12, 14 and 16 extendgenerally horizontally in use.

In the regulator 10 of FIG. 1 there are shown two louvre modulescomprising eight smaller louvre blades 12, two louvre modules comprisingseven medium louvre blades 14, two louvre modules comprising four largelouvre blades 16. In addition, one of the lower modules can have some ofthe louvre blades removed (or re-sized) to enable an access door to beprovided therein.

Each louvre blade is adapted at opposing ends for pivotal mounting in arespective module frame 20 (FIG. 2) to define a louvre module. In thisregard, each louvre blade is able to pivot around a lengthwise axis,between a closed or partially opened position in which the louvre bladescombine to close or restrict gas flow through at least a portion of thepassage, and an open position in which gas (typically air) is able toeasily flow between louvre blades and through the passage.

The same louvre module can be employed in both intake and exhaustraises, although the intake modules may require substantially lessbiasing than the exhaust raises (as described below).

As shown in FIGS. 3 and 8, the axis A may be offset with respect to alengthwise central axis of each louvre blade. Indeed the axis may belocated in a bar 22 mounted to either:

-   -   a front of the louvre blade and adjacent to an in-use lower edge        thereof (FIG. 3); or    -   a rear of the louvre blade and adjacent to an in-use upper edge        thereof (FIG. 8).

In the arrangement of FIG. 3 the louvre blades do not overlap in theclosed position, whereas in the arrangement of FIGS. 7 and 8 the louvreblades overlap in the closed position (ie. lower edge and rear face ofan upper louvre blade laps over the upper edge and front face of a lowerlouvre blade).

The overlapping arrangement is especially useful for an intake louvre asit results in the forcing of a seal, due to pressure on the louvre bladefront faces of passage ventilation air (FIG. 7A). The non-lappedarrangement (FIG. 3) can be used for an exhaust louvre. However, asstated above and for expediency, typically the same louvre module isused in both intake and exhaust louvre regulator positions.

Referring again to FIG. 1, the module frames 20 are mountable in alarger frame 30 arranged in and across the mine passage as shown inFIG. 1. A number of mounting pins or rock bolts 32 extend from the frame30 and are each adapted for being fastened with respect to (typicallyinto) adjacent walls of the mine passage. In this regard, the pins orbolts are fastened into the wall and then formwork is mounted to thepins or bolts. Thereafter a cementitious binder 34 (eg. shotcretecomprising steel fibre reinforcement) is sprayed onto the formwork toenclose the pins or bolts therewithin.

The frame 30 is typically also braced from the front (not shown) viatrusses/struts. For example, the frame can have heavy bracing at thefloor level in the form of two horizontal struts at the module joins.Two 45° braces can extend up from the floor level to the frame mid-pointto provide bending resistance in the vertical. Both sets of braces canbe joined and bolted to the floor, and both sets can possess pin-jointedconnections at the louvre frame. The braces are able to absorb much ofthe impact on the frame during firing/blasting.

Alternatively, the module frames 20 can be mounted in an alreadyexisting drop-board frame 40 (FIGS. 5 and 6) that may already bearranged in and across the passage.

A biasing mechanism for acting on each louvre blade is provided. In use,each blade is maintained in the predetermined position by the biasingmechanism until a stope firing, blast etc cause a predetermined airflowto act against the blades (eg. corresponding to a predetermined airpressure (or overpressure)).

In FIG. 3 it will be seen that one such biasing mechanism comprises aweighting arrangement operable on each louvre blade and that tends tocause it to pivot into a predetermined (closed) position (FIG. 3A). Theweighting arrangement comprises a weight bar 50 that is operativelycoupled to each louvre blade via respective linkage arms 52 which extendfrom respective coupling pivots 54. A coupling pivot 54 is connected toeach louvre blade end and, when rotated by the linkage, causes itslouvre blade to pivot about axis A. In this regard, the coupling pivot54 can be connected to each louvre blade end at the same point as theblade pivotal mount at bar 22 (ie. to be centred on axis A).

FIG. 4 shows the weight bar 50 in greater detail. In fact the bar maycomprise to back-to-back U-shaped channels 56 fastened together oneither side of linkage arms 52. Adjustable ballasts 58 can be mountedwithin either or both of the U-shaped channels 56, with the amount ofballast being regulated responsive to the airflow/pressure which thelouvre blades will be subjected to in use (eg. differential blastpressures, differential ventilation pressures at intake and exhaustlouvres etc).

In any case, under the influence of gravity the weight bar 50 urges downon the linkage arms 52 to pivot and maintain each louvre blade in thepredetermined (closed) position (FIG. 3A). Once a predeterminedairflow/pressure is reached (directed from left side of louvre blades inFIG. 3) the blades are urged by the air to be pivoted towards an openposition and now act on each linkage arm 52 against the weight of weightbar 50 (FIG. 3B). When the predetermined airflow/pressure subsides, theweight of bar 50 again urges down on the linkage arms 52 to pivot andreturn each louvre blade to the predetermined position.

The predetermined position may also correspond to a blade partiallyopened position, in which case the bar 50, via linkage arms 52, canpivot and return each louvre blade to this position, and this positionmay in turn be delineated by one or more appropriately positioned stopsacting on the bar, linkage arm(s) and/or blade(s).

The weighting arrangement may also comprise two (or more) spaced-apartweight bars, and when two weight bars are present they can be located oneither side of a louvre module.

In a first alternative to the weighting arrangement (or as an additionto the weighting arrangement), a spring mechanism that positively urgeseach louvre blade to pivot into the predetermined position can beprovided. The spring mechanism can comprise one, a number, or arespective spring for each blade. The spring(s) pull each louvre bladeinto the predetermined position, but at the predetermined airflow thelouvre blades act on and stretch the spring(s) as each louvre blademoves towards the open position.

The spring(s) can act between the frame and the lever arms or weightbar, or a respective spring can act on each louvre blade to urge it intothe predetermined position. For example, each spring can extend betweenthe frame and a mounting point located on the louvre blade at oradjacent to a leading or trailing edge of the blade.

Each spring may comprise a helical spring (eg. of steel), a leaf springetc. The tension in each spring may also be adjustable.

At the predetermined airflow/pressure the louvre blades act on andstretch the spring(s) as each blade pivots towards the open position,with the spring(s) returning each blade to the predetermined position asthe airflow/pressure subsides.

Referring now to FIGS. 9 to 17, where like reference numerals are usedin these Figures to denote like parts, a louvre module 60 comprises aframe 62 which is mountable into a larger frame (for example in largerframe 30), with the larger frame typically having been pre-arranged inand across a mine passage.

The module 60 comprises four large louvre blades 64, with each bladehaving a support shaft 65 affixed (eg. welded) to a rear thereof, andwith opposing ends of shaft 65 being pivotally mounted in a respectivepart of the frame 62 (see FIGS. 12 and 13). In this regard, each louvreblade is able to pivot around a lengthwise axis extending through theshaft 65, between a closed or partially closed (partially opened)position in which the louvre blades combine to close or restrict gasflow through the module, and an open position in which gas is able toeasily flow between louvre blades.

The frame 62 further incorporates two tyne-receiving lifting sleeves 66in a base member 68 thereof. The lifting sleeves 66 can each receivetherein a respective tyne of a forklift vehicle to enable module liftingand transfer to and from the larger frame.

Referring to FIGS. 10, 12 and 17, side members 70 of the frame 62 eachhave four spaced securing pin barrels 72 mounted thereto via angle ironbrackets 74. Each barrel houses a respective securing pin 76 for slidingtherein. A release bolt 78 is attached to and projects transversely fromthe pin 76 to travel in tracking 80 defined in the barrel 72. Thetracking 80 terminates at two locking slots 82 and 83 to accommodate anyvariations in the larger frame when mounting the module therein.

Each securing pin is slidable to extend beyond the periphery of frame 62and is lockable in that extended position by moving the bolt 76 into oneof the two locking slots 82 and 83. Thus, when the module has beenlocated in the larger frame (eg. via a forklift vehicle) extension ofthe pins secures the module to the larger frame.

Thereafter, retraction of the securing pins enables the module to bedetached from the larger frame. This provides a rapid and robust meansof mounting and demounting each module.

Referring now to FIGS. 10, 11, 13, 14 and 18 a biasing mechanism foracting on each louvre blade is provided behind a protective cover plate84 connected to extend upwardly from frame base member 68. In use, eachblade is maintained in a predetermined (eg. closed) position by thebiasing mechanism until a stope firing, blast etc causes a predeterminedairflow A (FIG. 14) to act against the blades (with the airflowcorresponding to a predetermined air pressure (or overpressure)).

In FIGS. 14 and 15 it will be seen that the biasing mechanism comprisesa gas strut 86. The strut 86 has a housing 88, with a rod 90 beingconnected to the frame base member 68 at pin mounting arrangement 92.The housing 88 is moved by gas pressure in the strut up along rod 90 togenerally be urged up with respect to the frame 62 (in the direction ofarrow F—FIG. 15). This movement imparts the self-closing tendency in thebiasing mechanism.

In this regard, and as best shown in FIGS. 15 and 16, an upper end ofthe housing 88 has upwardly extending lugs 94 fastened thereto, witheach lug having a hole therethrough. The lugs 94 receive a downwardlyextending lug 96 therebetween, with lug 96 also having a holetherethrough. Lugs 94 are connected to lug 96 via a retention pin 98.The lug 96 extends downwardly from a plate 100, with the plate 100 inturn being connected to a linkage bar 102 for louvre blade adjustment(as described below).

To control the amount of louvre blade closure an adjustment mechanism isprovided. This mechanism comprises opposing spaced guide rods 104, eachwith a plurality of holes 105 defined therethrough. Each rod 104 is alsoconnected to the frame base member 68 at a respective pin mountingarrangement 106 and extends upwardly therefrom and through apertures inthe plate 100. The rods can thus help to guide plate movement up anddown. An adjustment pin 108 is insertable through a selected one of theholes 105 of each rod 104 to extend between the rods as best shown inFIG. 15. As shown, the pin 108 sits above plate 100 and therebyrestricts its upward travel, being that travel resulting from the gasstrut urging upwardly on the plate. Because the plate is connected tothe linkage bar 102 for louvre blade adjustment, the extent of louvreblade closure can thus be controlled through appropriate location of theadjustment pin 108.

FIGS. 10 and 11 shows a variation on the adjustment pin 108. An elbow109 extends from the pin and can extend through the next overlying hole105. A retaining clip 109A can fasten an end of the elbow into position,to fasten the pin 108 in place.

In this regard, the linkage bar 102 is pivotally connected to a doublebracket arrangement 110 (as best shown in FIG. 13). Each of the doublebrackets in an arrangement 110 is, at one end, fixed (eg. welded)adjacent to an upper edge of a respective louvre blade 64. The oppositeend of each of the double brackets pivots about a pin 112 extendingthrough a hole (eg. 114) at linkage bar 102.

Thus, when the louvre blades are each at least partway open (eg. from anincrease in passage air pressure) to self-close the blades the gas strutacts to move the strut housing 88 upwardly. This urges plate 100upwardly, which simultaneously urges linkage bar 102 upwardly, causingthe double bracket arrangement 110 to pivot upwardly (ie. around thelengthwise axis of the louvre blade shaft 65). This causes each of thelouvre blades 64 to be moved back towards the predetermined (eg. closed)position, with the gas strut then tending to maintain each louvre bladein this position. However, pin 108 can be employed at various positionsalong the rods 104 so that plate 100 will engage the pin, therebystopping louvre blade movement to the fully closed position (with thisstop resistance being depicted by arrow S in FIG. 15). Hence the pin 108can be used to maintain the louvre blades in a partially closed(partially open) position. For example, pin 108 may be employed when itis desirable or necessary to allow some, or a normal/natural flow levelof eg. air in the passage in which the module 60 is employed.

Arrow A in FIG. 14 depicts a predetermined airflow/pressure beingreached whereby the blades 64 are urged by the airflow to be pivoted (inthe direction of arrow P in FIG. 14) towards an open position. Thiscauses the linkage bar 102 (via the double bracket arrangement 110 andplate 100) to be moved against the gas strut force F, causing the struthousing 88 to be driven downwardly along rod 90. When the predeterminedairflow/pressure has subsided, the gas strut again urges the plate 100and thus the linkage bar 102 upwardly to pivot and return each louvreblade to the predetermined position (partially or fully closed).

Because the gas strut can be interchanged, different self-closing forcescan be selected based on a given strut's specifications. The strutitself may also be adjustable, such that it is only compressible once acertain air pressure (eg. from a stope firing or blast) is reached.

Usually the regulator comprises a control mechanism to separately andindependently control the position of each louvre blade during normalairflow control in the mine passage (ie. for the flow control ofnon-blast generated airflow). In this regard, the biasing mechanism doesnot interfere with the control mechanism during such normal airflowcontrol. Conversely the control mechanism does not interfere withopening of the louvre blades at the predetermined airflow or withbiasing mechanism blade return to the predetermined position. In otherwords, these mechanisms operate independently of each other.

The control mechanism can be manually adjustable or comprise a remotelycontrolled adjustment mechanism. The remotely controlled adjustmentmechanism employs actuators that are electrically operated and remotelycontrolled via a fibre optic communication system located at a surfaceof the mine to adjust the blades to a set position. The actuators canoperate in conjunction with air flow meters located at each regulatorsite, and an operator typically remotely adjusts the blades to obtain adesired airflow under normal mine operating conditions.

The manually adjustable mechanism can provide for multi-blade-positionadjustment, whereby the louvre blades can be maintained at a number ofdifferent positions using locking pin(s). However, this adjustment mustbe performed in situ by an operator.

The regulator typically comprises a stop in the form of a dampener orshock absorber for preventing/restricting blade pivotal movement beyondthe open position (typically a blade fully open position). A dampener orshock absorber can be provided for each blade, or again one or just afew dampeners or shock absorbers may be arranged to act on the weightbar or the linkage arms. Each dampener or shock absorber can absorb themomentum of one or more rapidly pivoting blades under the influence ofan air blast.

EXAMPLES

Non-limiting examples of louvre-based regulators will now be described.

Example 1 New Louvre Construction

In the construction of a new louvre regulator such as shown in FIG. 1,rock bolts were first installed into the mine wall. Pins, consisting ofRHS steel section, were then cut to length, welded to the rock bolt andthen welded to the larger regulator frame. At each attachment point twopins or braces were provided, one being directly in line with the frameand one extending at 45 degrees thereto, to provide a truss like effect.

Formwork was then mounted to the pins/bolts and shotcreting took place(typically a wet process concrete spraying with the concrete comprisingsteel fibre reinforcement). A standard frame generally required 5 cubicmetres of concrete to meet structural requirements.

The applicant noted that the time for construction of the louvreregulator of FIG. 1 could in many mines take up to three 12 hour shifts(a substantial down-time cost), with the cost of providing the regulatorwith a new shotcrete surround also being substantial. Thus, for manymines (especially existing mines) it would be easier to simply installseparate modules into each existing regulator site.

Example 2 Louvre Retrofit to Drop-Board Frames

Rather than replacing the existing drop-board surrounds, louvre moduleswere designed that could be retrofitted into eg. a known six partitiondrop-board regulator frame.

FIGS. 5 and 6 schematically depict part of a steel drop-board regulatorframe 40 to which the louvre modules could be mounted. Known frames wereconstructed from 150 UC30 section and comprised three verticalpartitions 60, each divided into a top and bottom half by horizontalpartitions 62. In some of the drop-board regulator frames examined,partitions were missing, however were easily welded back into place.

Then, in each drop-board regulator frame the timber slabs were removedand six louvre modules 20 were then positioned within the frame.However, prior to positioning the louvre modules within the frame fourlugs were welded onto the sides of each module to be slotted into theregulator frames and the modules were then dropped down to fit insidethe existing frame. Any gaps were able to be covered by steel coverplate.

Five of these frames were fully bladed and the sixth (right-hand lowersection) contained a man-door together with some of the louvre blades(optionally modified in length, width etc).

Advantages of using modules included their rapid and easy removal (eg.for repairs, replacement) and their ability to be installed within anyexisting frame in the mine.

Example 3 First Trial Louvre-Type Regulator

An initial trial louvre regulator design employed a normal airflowcontrol mechanism using manual fixing of the louvre blades in eachmodule via linking rods to a rigid manual blade adjustment mechanism(but which could also employ a motorised drive).

Before stope firing the blades were moved to a fully opened position andwere locked into place. The trial louvre design was subjected to severalblasts, and it was observed that the closest blast caused damage to theblades and their attached blade mounting shafts. In some trials, whenstope firing took place on the same level as the louvre, the blades andshaft attachment were so damaged that the module was renderedinoperative.

In the trials it was also noted that the air-blast from firings withinsurrounding levels subjected the louvre blades to forces from otherdirections (eg. originating from the raise). Even though thisrepresented the least flow resistance to an air blast, the swirlingaction of the turbulent air was observed to subject the blades andattached linkages to excessive pressures, thereby potentially sustainingdamage.

The applications of regulators comprising manually controlled louvreblade adjustment was therefore considered to be more limited.

Example 4 Second Trial Louvre-Type Regulator

As discussed in Example 3, the initial trial louvre regulator designincorporating manual louvre blade adjustment did not satisfy alloperating conditions within the mine and, it was noted, would likelysustain damage at some stage, rendering it inoperative. A second triallouvre regulator design was conceived (a so-called “MkII” design) whichwas designed to minimise the damage to the louvre blades, attachedlinkages and frame structure. The MkII design was developed to lessenthe initial impact on the frame that secured the components.

In this regard, in the MkII design the blades (and any linkages) werefree to move during a firing and did not absorb as much energy as amanual blade fixing system. The blades were therefore self-adjusting.

In the design and construction of the MkII design, the following designfeatures were developed:

1. The louvre blade pivot point was located as close to the leading edge(edge closest to the air-flow from within the adjacent stope) aspossible so that damage was minimised during stope firing. Also, for theblades to hang freely and close against each other the pivot point waslocated close to the leading edge.2. The blade design had a low resistance to passing air so that energylosses were minimised.3. The louvre blades were self-adjusting such that, before stope firing,mine ventilation officers did not have to make any adjustment to thelouvre.4. The blades within a louvre module rotated freely on their shafts andcould self-closed under mine ventilation pressures (except at blastingoverpressures).5. The blades were fabricated to be sufficiently heavy to assist inachieving movement to a predetermined position (closed or partiallyopen) against ventilation pressures.6. The required weighting was different for louvre regulators situatednext to intake passages compared to those situated next to exhaustpassages.7. There was no restraint on the blades being able to fully open (eg.towards horizontal) from a set position (predetermined—closed orpartially open) during firing and the blades dropped back (fell) to thepredetermined position even after being further opened by the blast.8. A pre-set guide (eg. stop) was not rigidly attached to the bladelinkage.9. The louvre frame was braced from the front, as there was no bracingaccess from the rear (or within the raise) in use.10. An option to have one of the in-use bottom modules hinged, to enableuser access through the louvre regulator, as necessary.11. The blades could be independently coupled to an actuator (eg.employing a motor drive) for normal airflow control in the raise.

Example 5 Exhaust and Intake Louvre-Type Regulators

FIGS. 7A and 7B respectively and schematically illustrate louvreregulators subject to intake or exhaust pressure. A typical maximumventilation pressure within any raise was noted to be up to 2000 Pa(with the maximum fan pressure at the top of the raise as illustrated).This pressure was dissipated as air traveled through a raise and/or asair paths were split. This pressure was used for the design of thelouvre blades.

In the intake louvre regulator of FIG. 7A a stope airblast lifted thelouvre blades, whereas ventilation air pressure tended to close theblades.

In the exhaust louvre of FIG. 7B both the stope airblast and theventilation air pressure lifted open the blades. Thus, blade weight and,where necessary, additional weighting and/or spring biasing was employedto counteract ventilation air pressure lift on the louvre blades andmaintain them in the predetermined position. To further assist bladeself-closure:

1 A blade design was employed that located the blade pivot point towardsits top edge;2 A blade design was employed where the blade was tilted so that acomponent of the blade weight resisted the ventilation air-flow;3 The weight distribution of the blade was closely examined.

Example 6 Louvre Blade Design

Calculations were performed to determine whether a louvre blade weightcould be employed that would resist the force of the ventilating air.The calculations assumed that the blade shaft was offset towards theblade top and that the blades sat against each other in a tiltedconfiguration (FIG. 8).

The calculations were based on a blade that was 475 mm wide,manufactured from 8 mm plate and, for simplicity, was 1 metre in length.The blade was assumed to be welded to a 30 mm diameter shaft and offset100 mm, giving 100 mm overlap for each pair of adjacent blades. Theblade shaft centres were assumed to be spaced 375 mm. It was assumedthat the offset blade design needed to resist a 2 kPa ventilationpressure without opening. The calculations were as follows:

$\begin{matrix}{{{Blade}\mspace{14mu} {weight}} = {0.008 \times 0.475 \times 9800\mspace{14mu} N}} \\{= {360.3\mspace{14mu} N}}\end{matrix}$

In FIG. 8 offset blades are shown attached to 30 mm shafts centred on anaxis A. In FIG. 8:

F_(s) is the resultant force of a steel blade;

F_(v1,2) are the forces on the blade due to the ventilation exhaust air.

Air pressure was resolved into equivalent forces about a line of thrustas shown.

F_(v1)=0.275×1×2000=550 N (lever arm 137.5 mm)F_(v2)=0.100×1×2000=200 N (lever arm 50.0 mm)

By resolving moments about the centre A of the shaft it was determinedwhether the blade force was sufficient to close against the ventilationpressure.

Hence

$\begin{matrix}{M_{A} = {{{365.3\lbrack N\rbrack} \times {21.93\lbrack{mm}\rbrack}} + {{200\lbrack N\rbrack} \times {50\lbrack{mm}\rbrack}}}} \\{= {18\mspace{14mu} {{kN}.{mm}}}}\end{matrix}$

Ventilation pressure on the blade below the shaft should thereforeresist the moment M_(A). The moment due to the ventilation pressure onthe portion of the blade below the shaft was:

 = 550[N] × 137.5[mm] = 75.625  kN.mm

The imbalance of 57.6 kN.mm needed to be overcome in order to maintainthe blades in the predetermined position. The following possibilitieswere then considered as possible solutions:

1 Add a solid block of 40 mm square steel to the blade tip (but this wascalculated to provide only an additional 7.845 kN.mm).2 Offset the blade another 50 mm from pivot A (but this was calculatedto add only another moment of 50×365.3=18.27 kN.mm).

Thus, an increase in blade weight and/or an increase in the blade pivotarm were each calculated to be insufficient in overcoming theventilation air pressure. In addition, because the blade edges sealagainst the frame, the amount of offset was accordingly limited.Centralizing the pivot point A was noted to balance the ventilationpressure on the blade, however the blades could then sustain damageduring a stope firing/blast.

Thus, one solution as outlined in the description of FIG. 3 wasdeveloped, namely, arranging a balance weight on the raise side of eachmodule, the weight being attached to blades via respective lever arms.This ensured the blades were maintained in the predetermined positionunder normal ventilation pressures.

Typically a steel weight was employed. The option of guiding andcontaining the steel weight's movement up and down within a pipe wasalso investigated. A return spring mechanism was also noted to performthe same function and was advantageously also tension adjustable.

It was noted that further experiments were to be conducted to measurethe pressure-time profile of the effects of production firing at a trialsite. Software was to be written to describe the forces on each louvrecomponent at any given blade angle or at any given time. The softwarewas to have as input the pressure time profile for any overpressureevent.

Example 7 Exhaust Louvre-Type Regulator Design Solution

Referring again to FIGS. 3A and 3B an exhaust louvre is schematicallydepicted. This design was based on incorporating a weight that can actagainst a 1000 Pa ventilation pressure on 300×1200 mm blades (anapproximate louvre module size). The total mass of each weight bar onopposing sides of a module was 54 kg (a bar located on one side of thelouvre could have a bar weight of approximately 108 kg).

In operation of the exhaust louvre it was noted that as the louvreblades opened the resistance to airflow lessened (ie. the lever armeffectively shortened) with each blade becoming easier to open the moreopen it became. This had a tendency to lessen the blast impact on theblades and structure as a whole.

Ideally the link bar weight was adjustable (eg. using the ballast).Also, because the blades had a tendency to accelerate as they shut theregulator design needed to account for impact against a set-pointmechanism.

Example 8 Louvre Blade, Module and Frame Fabrication

Each louvre blade was formed from painted mild steel (350 grade steel).The painting of the steel louvre was undertaken after sandblasting.Frames were also formed similarly. A two-part epoxy paint (Joatacoat605) was employed to provide effective corrosion protection. Such paintwas found to give good results in underground mines where knownventilation controls painted with such paint did not need to berefurbished until after a period of six years.

316 stainless steel was used for louvre shafts, and nylon bushes wereemployed at the blade mountings.

Design Specifications

The louvre modules were designed to control airflow to surface airraises that service up to six or seven levels within each part of amine. Each louvre blade, module and frame:

-   -   Was designed to withstand a blast overpressure of 5 psi (34        kPa);    -   Was manually adjustable by one operator without assistance;    -   Typically had an opening size 4.5 metres in height and 3.5        metres in width;    -   Had a modular construction so that its configuration was        variable;    -   Was able to be shotcreted into place;    -   Was able to be controlled remotely;    -   Was unaffected by ground movement during installation;    -   Was corrosion resistant (eg. to saline water vapour present in        down-casting air);    -   Had the option for control in pairs of modules, whereby eg.        three actuators could fully open or fully close the louvre        blades. To provide incremental airflow control, additional        controls could be added to the actuators.

Louvre Modules

The louvre regulator typically comprised six equally sized removablemodules, each with a set of horizontal louvre blades for ease of removaland replacement of damaged modules (see FIG. 1). Lifting lugs wereprovided for the safe removal of each module.

In a manual control version, horizontal louvre blades were able to beset in multiple positions. In such case, the louvre blades in eachmodule were adjustable to and lockable in the positions: Open, 20%, 40%,60%, 80% and Closed.

The louvre framework was also able to be welded to existing drop-boardregulator steel frames, however each such application required carefulexamination and measurement for compatibility.

Louvre Automation

Automatic (and remote) control of blades in each louvre blade frame wasachieved using a Tyco double acting electric actuator, which employs arack and pinion, with the pinion connected to the louvre blades viaconnecting rods. These actuators could easily be remotely controlled.The actuators also had an anodised aluminium body to protect againstcorrosive environments. Three actuators were mounted on a horizontalframe that separated each pair of louvre modules.

Example 9 Louvre-Based Regulator Advantages

In a self-adjusting louvre-type regulator:

-   -   The ventilation officers did not have to adjust the louvre        before and after a stope firing.    -   Blades were free to swing away from the blast during a stope        firing.    -   Blades returned to their original (predetermined) positions        after a stope firing.    -   Returned blades remained in the predetermined position against        the normal mine ventilation flow, and in the closed position        provided better sealing performance than known regulators,        especially with blade overlap.    -   Blade modules were able to be retrofit into existing drop-board        regulator frames.    -   Regulators were provided that were suitable for use within        corrosive saline environments and that required minimal        servicing.

Where an adjustment mechanism was employed with the self-adjustinglouvre-type regulator it did not need to be directly attached to thelouvre blade controls, and could comprise a simple mechanism.

Whilst specific embodiments of a louvre-type regulator have beendescribed, it should be appreciated that the regulator can be embodiedin many other forms.

1. A louvre-type airflow regulator for a mine passage comprising: aplurality of louvre blades, each adapted for mounting in a frame andpivoting therein around a lengthwise axis between a predeterminedposition in which the louvre blades combine to close or restrict atleast a portion of the passage, and an open position in which air isable to readily flow between the louvre blades and through the passage;a biasing mechanism for acting on each louvre blade such that, in use,each louvre blade can be maintained in the predetermined position untila predetermined airflow against the louvre blades is reached; whereinthe predetermined position is adjustable and includes at least onepartially open position of the blades between a closed position and afully open position.
 2. (canceled)
 3. A regulator as claimed in claim 1wherein the biasing mechanism is: (i) a weighting arrangement operableon each louvre blade and that tends to cause it to pivot into thepredetermined position; (ii) a spring mechanism that positively urgeseach louvre blade to pivot into the predetermined position; and/or (iii)a strut mechanism that positively urges each louvre blade to pivot intothe predetermined position.
 4. A regulator as claimed in claim 3 whereinin: (i) the weighting arrangement comprises one or more weightsoperatively coupled to each louvre blade via a respective linkage,whereby due to gravity the weight(s) draw down on the linkages andthereby urge each louvre blade into the predetermined position, but atthe predetermined airflow the louvre blades then act on each linkage andurge the weight(s) up as each louvre blade moves towards the openposition; (ii) the spring mechanism comprises a respective spring thatpulls each louvre blade into the predetermined position, but at thepredetermined airflow the louvre blades act on and stretch eachrespective spring as each louvre blade moves towards the open position;and/or (iii) the strut mechanism is a gas strut that is connected to alinkage mechanism that acts on the louvre blades to urge them into thepredetermined position, but at the predetermined airflow the louvreblades act on the linkage mechanism which in turn acts against the gasstrut as each louvre blade moves towards the open position.
 5. Aregulator as claimed in claim 4 wherein in: (i) the weightingarrangement comprises one or two weights, with each weight having thelinkages extending therefrom at intervals spaced along the weight, andwith each linkage being coupled to a respective louvre blade at acoupling that is pivotally mounted to the frame at the same point as theblade pivotal mounting; (ii) each spring extends between the frame and alocation on the louvre blade at or adjacent to a leading or trailingedge of the blade; and/or (iii) the connection between the gas strut andthe linkage mechanism is adjustable such that the louvre blades caneither be fully or partially closed by the operation of the gas strut.6. (canceled)
 7. (canceled)
 8. (canceled)
 9. A regulator as claimed inclaim 1 further comprising the frame, and a plurality of mountingpins/bolts extending from the frame and adapted for being fastened withrespect to adjacent wall(s) of the mine passage.
 10. A regulator asclaimed in claim 9 wherein the pins are used for the mounting offormwork that provides at backing for the application of a cementitiousbinder, whereby the pins/bolts, formwork and binder then provide astructural wall to support the frame in the passage.
 11. A regulator asclaimed in claim 1 wherein the frame forms part of a module, with aplurality of such modules being mountable in a larger frame arranged inthe passage.
 12. A regulator as claimed in claim 11 wherein each modulehas a plurality of selectively extendable securing pins arranged aroundits periphery such that, when the module is mounted in the largerpassage frame, extension of the securing pins secures the module to thepassage frame, and retraction of the securing pins enables moduledetachment from the passage frame.
 13. A regulator as claimed in claim11 wherein each module has lifting points formed therein that enable itto be lifted into and out of the passage frame.
 14. A regulator asclaimed in claim 1 further comprising a stop for preventing bladepivotal movement beyond the open position.
 15. A regulator as claimed inclaim 14 wherein the stop comprises a dampener or shock absorber.
 16. Aregulator as claimed in claim 1 wherein the blades extend generallyhorizontally in the frame in use.
 17. A blast proof regulator for a minepassage comprising: a plurality of louvre blades, mounted in a frame andpivoting therein around a lengthwise axis between at least apredetermined position in which the louvre blades combine to close orrestrict at least a portion of the passage, and an open position inwhich air is able to readily flow between the louvre blades and throughthe passage; a biasing mechanism for acting on each louvre blade suchthat, in use, each louvre blade can be maintained in the predeterminedposition until a predetermined airflow against the louvre blades isreached; wherein the predetermined position is adjustable and includesat least one partially open position of the blades between a closedposition and a fully open position; and wherein the louvre blades areadapted to pivot open at a predetermined airflow in the mine passage andreturn to their respective predetermined positions after removal of thepredetermined airflow.
 18. A blast proof regulator as claimed in claim17 wherein a plurality of frames are mountable in a larger framearranged in the mine passage.